Embodiments of the present invention generally relate to emission detection methods and devices (e.g., fluorescence microscopes). More specifically, certain embodiments relate to techniques for improving emission detection devices in applications such as microscopy and cytometry.
Fluorescence techniques are widely used in biomedical imaging and sensing to identify or detect microscopic structures, submicroscopic structures, even individual molecules. A fluorescence signal measured by devices using fluorescence techniques can also reveal cell dynamics and metabolism. An example of a fluorescence technique can be found in Giloh, H., and Sedat, J. W., “Fluorescence microscopy: reduced photobleaching of rhodamine and fluorescein protein conjugates by n-Propyl Gallate,” Science 217, 1252-1255 (1982), which is hereby incorporated by reference in its entirety for all purposes. An example of a fluorescence technique that can identify submicroscopic structures can be found in Betzig, E., et al., “Imaging intracellular fluorescent proteins at nanometer resolution,” Science 313, 1642-1645 (2006) and Bates, M., et al., which is hereby incorporated by reference in its entirety for all purposes.
Conventional fluorescence microscopes are common tools that use fluorescence techniques to investigate biological problems. Usually, a reagent (e.g., fluorescence/phosphorescence dye) is mixed with a sample to mark or tag portions of the object (e.g., cell) under investigation with fluorophore(s). A fluorophore refers to a component of a molecule that causes the molecule to fluoresce or phosphoresce once excited. A fluorophore can absorb energy from excitation light of a specific wavelength(s) and re-emit the energy at a different wavelength(s). A conventional fluorescence microscope irradiates the sample with excitation light of predetermined wavelength(s) (e.g., blue light) to activate fluorophore(s) in the sample. In response, fluorophore(s) release fluorescence/phosphorescence emissions of different wavelength(s) (e.g., red light). Most conventional fluorescence microscopes include filters to reject excitation light and allow the weaker fluorescence/phosphorescence emissions signal to be detected.